1. Field of the Invention
The present invention relates to lighting, and more particularly, to low-clearance lighting. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for providing low-clearance lighting for either drop-ceilings, drywall/plaster ceilings or walls.
2. Discussion of the Related Art
In general, drop-ceilings are typically installed in commercial buildings. However, drop-ceilings can also be installed in residences, such as during basement remodeling. FIG. 1A is a perspective view of a drop-ceiling having ceiling-grid with a lighting unit according to the related art. As shown in FIG. 1A, horizontal rails 1a and vertical rails 1b create a ceiling-grid 1 with openings in which ceiling tiles 2 are positioned. The ceiling-grid 1 shown in FIG. 1A is, for example, a two foot by two foot ceiling-grid. As also shown in FIG. 1A, the related art lighting unit 3, such as a fluorescent fixture, can also be positioned in the ceiling-grid 1. The related art lighting unit 3 has the same standard size or outside dimensions as the ceiling tiles 2.
Drop-ceilings are easy to install because the ceiling-grid can be hung by wire-hanger, which can be readily attached to the overhead ceiling. The use of the wire-hangars enables simple attachment and leveling of the drop-ceiling. A drop-ceiling covers up the electrical wires, ventilation equipment and plumbing that can run along an overhead ceiling. The electrical wires, ventilation equipment and plumbing above the drop-ceiling are easy to access through the ceiling-grid by removal of the ceiling tiles. However, a drop-ceiling requires a minimum clearance between the overhead ceiling and the drop-ceiling.
FIG. 1B is a cross-sectional view of a ceiling having ceiling-grid with a lighting unit along the line I-I′ of FIG. 1A. As shown in FIG. 1B, the back of the related art lighting unit 3, which resides in an opening of the ceiling-grid 1, extends from the ceiling-grid 1 to a lighting unit height HLU above the ceiling-grid 1. The lighting unit height HLU above the ceiling-grid 1 can be about five to six inches, depending on the depth D of the related art lighting unit 3. A minimum insertion height HMI is needed in addition to the lighting unit height HLU so as to be able to insert the related art lighting unit 3 into the ceiling-grid 1. The minimum insertion height HMI of the related art lighting unit 3 can be about four to six inches. Thus, the minimal lighting clearance height HMLC that a drop-ceiling must have to receive the related art lighting unit is the sum of the lighting unit height HLU and the minimum insertion height HMI, as shown in FIG. 1B. Accordingly, the minimal lighting clearance height HMLC that a drop-ceiling must have to receive the related art lighting unit can be about nine to twelve inches.
Typically, the minimum clearance between an overhead ceiling and a drop-ceiling is limited by the minimal lighting clearance height HMLC. Thus, the minimal lighting clearance height HMLC of the related art lighting unit dictates the drop-ceiling height HDC over the floor, as shown in FIG. 1B. In other words, the maximum drop-ceiling height HDC is usually limited by the minimal lighting clearance height HMLC.
Unlike drop-ceilings, a drywall/plaster ceiling is attached directly to either roof joists or floor joists. The related art lighting units in drywall/plaster ceilings are placed between the joists to accommodate the lighting unit height HLU of the related art lighting units. However, the size of the related art lighting units is limited to the spacing between floor/ceiling joists. Further, the placement of related art lighting units in a drywall/plaster ceiling is restricted because of the need for the related art lighting units to be placed between floor/ceiling joists.